H1N1 is a flu virus that was initially referred to as the swine flu. It was first detected in the United States in April of 2009. It causes flu-like symptoms including, fever, cough, fatigue and muscle aches. Scientists call the H1N1 virus a "quadruple reassortant" virus. This is because the virus contains two genes found in flu viruses which circulate among pigs, and two genes that circulate in flu viruses among birds (avians). The virus was originally called swine flu because of the genes, which are similar to that of flu viruses in pigs. The H1N1 flu virus is passed from person to person just like other flu strains. You cannot catch swine flu from eating pork.
What sets H1N1 virus apart from other seasonal flu viruses is that studies have shown it to cause more severe symptoms in people younger than 25. Also, many people older than 60 years of age have some immunity against the H1N1 virus.
Most cases of flu caused by H1N1 are mild, however, there have been some hospitalizations and deaths. Many of the people who have severe complications from H1N1 have other medical conditions, such as pregnancy, diabetes, heart disease, kidney disease and asthma.
Scientists are working on creating a vaccination for H1N1 and clinical trials have already begun. In the meantime, anti-viral drugs such as Tamiflu have been helpful in treating H1N1.
CDC. H1N1 Flu and You. Accessed: August 6, 2009 from http://www.cdc.gov/h1n1flu/qa.htm